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目的探讨一氧化氮供体L-精氨酸(L-Arg)对大鼠不同病程阶段的急性肺损伤(ALI)的影响及机制。方法采用注射内毒素脂多糖(LPS)的方法制备大鼠肺损伤模型。健康雄性SD大鼠,随机分为:①对照组;②LPS组;③L-Arg治疗组。各组按治疗时间又分为给LPS1h后治疗3h(1h+3h)组和给LPS6h后治疗3h(6h+3h)组,并在给予LPS1和6h后再分别ip给予生理盐水(对照组及LPS组)和L-Arg500mg.kg-1(L-Arg治疗组)治疗3h。采用流式细胞术检测肺细胞凋亡率;Western蛋白印迹法检测胱天蛋白酶3(caspase3)蛋白的表达;免疫组化法测定Bcl-2和Bax蛋白的表达;电镜观察肺组织病理变化。结果与对照组比较,LPS1h+3h及LPS6h+3h组细胞凋亡率和caspase3蛋白表达明显升高,Bcl-2蛋白表达下降,Bax表达增加,Bcl-2/Bax比值降低,肺组织出现明显的病理变化。与LPS1h+3h组相比,L-Arg1h+3h组细胞凋亡率〔(23.8±2.8)%vs(15.4±2.3)%〕,caspase3(0.80±0.06vs0.67±0.10)和Bax蛋白表达(0.115±0.012vs0.091±0.014)显著降低,Bcl-2蛋白表达(0.067±0.011vs0.075±0.009)和Bcl-2/Bax比值(0.586±0.114vs0.833±0.142)显著升高;肺组织病理改变明显减轻。L-Arg6h+3h组细胞凋亡率和caspase3蛋白表达低于LPS6h+3h组,肺组织病理改变稍有减轻。结论较早给予L-Arg可减轻ALI,其机制可能与降低caspase3和Bax蛋白表达、增强Bcl-2蛋白表达有关。
Objective To investigate the effect of L-arginine (L-Arg) on acute lung injury (ALI) in rats at different stages of disease. Methods The rat model of lung injury was prepared by injection of lipopolysaccharide (LPS). Healthy male SD rats were randomly divided into: ① control group; ② LPS group; ③ L-Arg treatment group. Each group was divided into three groups according to the treatment time: 3h (1h + 3h) after LPS1h treatment and 3h (6h + 3h) after LPS6h treatment, and then were given normal saline (control group and LPS Group) and L-Arg500mg.kg-1 (L-Arg treatment group) for3h. The apoptosis rate of lung cells was detected by flow cytometry. The expression of caspase 3 protein was detected by Western blotting. The expressions of Bcl-2 and Bax protein were detected by immunohistochemistry. The pathological changes of lung were observed by electron microscope. Results Compared with the control group, the apoptotic rate and the expression of caspase3 protein in LPS1h + 3h and LPS6h + 3h groups were significantly increased, the expressions of Bcl-2 protein, Bax protein and Bcl-2 / Bax protein were significantly decreased Pathological changes. Compared with LPS1h + 3h group, the apoptotic rates of L-Arg1h + 3h group were (23.8 ± 2.8)% vs (15.4 ± 2.3)%, caspase3 (0.80 ± 0.06 vs 0.67 ± 0.10) 0.115 ± 0.012vs0.091 ± 0.014), the expression of Bcl-2 protein (0.067 ± 0.011vs0.075 ± 0.009) and Bcl-2 / Bax ratio (0.586 ± 0.114vs0.833 ± 0.142) Pathological changes significantly reduced. The apoptosis rate and the expression of caspase 3 protein in L-Arg6h + 3h group were lower than those in LPS6h + 3h group, and the pathological changes in lung tissue slightly lessened. Conclusion L-Arg can reduce ALI earlier, which may be related to the decrease of caspase3 and Bax protein expression and the increase of Bcl-2 protein expression.